Using JPQL in JPA

This example is using JPQL and executing select query to get multiple result from table. Here Employee is the name of entity class not a table name in database and emp is a alias for Employee entity. Query object is used to represent a query and it has getResultList method that returns list of multiple entities for each row fetched from database using JPA.


import java.util.*;
import javax.persistence.*;
public class JavaApp2
{
    public static void main(String ar[]){
        
        EntityManagerFactory emf=Persistence.createEntityManagerFactory("persistunit");
        EntityManager em=emf.createEntityManager();
        Query q=em.createQuery("SELECT OBJECT(emp) FROM Employee emp");
        List<entities.Employee> rl=q.getResultList();
        for(entities.Employee e:rl){
            System.out.println("- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -- - - ");
            System.out.println("\t"+e.getId()+"\t"+e.getName()+"\t"+e.getSalary()+"\t"+e.getDesignation());
        }
    }
}

Generating Primary keys in JPA 

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